Jump to content

Weird 'cosmic' tube sound: faulty tube? Help needed


MeloManiac
 Share

Recommended Posts

I've been enjoying my Leben CS300 with one year old Gold Lion tubes.

Recently I noticed weird 'cosmic' sounds in the upper frequencies in one channel. It is a weird 'cosmic' sound, like electrons working in the tube. It wasn't constant and not loud, just enough to draw the attention. For fear of damaging the amplifier, I took out all the the EL84 Gold Lion tubes and replaced them with the original Sovtek EL84 tubes. Now, the weird sound is gone. 

I think one of the Gold Lion tubes is faulty.

How can I test which one of the four?

I live in a rural town and have don't know anybody who can work on tubes (in fact, I don't know anybody else who owns a tube amplifier, except the members of this forum).

Can I mix different brands of tubes? I have two Sovtek EL84M tubes?

As the weird sound is not constant, it is hard to find out which tube is faulty by replacing them one by one. I think they need to be measured instead. The CS300 does auto-bias, btw.

 

Help appreciated!

 

 

  • Like 1
Link to comment
Share on other sites

Mixing brands is fine.  With intermittent tube problems it is easier to replace the suspect than to try to figure out what is going on.  A tube tester rarely picks up such issues.  With push-pull stages I recommend replacing the pair and buying from a seller who can match them using a curve tracer.

 

Maynard

  • Like 2
Link to comment
Share on other sites

10 hours ago, MeloManiac said:

it is hard to find out which tube is faulty by replacing them one by one

Haha; only takes "one" swap.  Replace left (or right) tubes with the Sovtek's. If the problem goes away, one of these Gold Lions was bad. If the problem remains it is in the "other" tubes.  Note; you need to replace them as a matched pair, so that made troubleshooting easier :) 

But, you'll probably want to replace all anyhow. These tubes generally last only 1-2 years ... yes; consumables as per @Schu

  • Like 1
Link to comment
Share on other sites

Tubes are consumables,  no doubt ...and when I get noise I root out the problem immediately to prevent damage to my babies....   I had a weird screechey , other worldly sound recently and it was a new driver tube.  Tube was only a few weeks old.    I first will clean all tube pins with 99.9 iso and sockets as well that often gets rid of the noise,  but any weird noises after that I replace tube in question

Link to comment
Share on other sites

1 hour ago, Steve. said:

Tubes are consumables,  no doubt ...and when I get noise I root out the problem immediately to prevent damage to my babies....   I had a weird screechey , other worldly sound recently and it was a new driver tube.  Tube was only a few weeks old.    I first will clean all tube pins with 99.9 iso and sockets as well that often gets rid of the noise,  but any weird noises after that I replace tube in question

 

Good advice in this thread.

 

I had a NOS 7F8 that looked great but screeched like a banshee. Scared the crap out of me...

 

 

Link to comment
Share on other sites

10 hours ago, MeloManiac said:

I thought new tubes would last up to 10,000 hours of play.

4 replacement EL84 tubes cost 52 euro; I think I'll order them.

 

Thanks for the advice.

 

It depends.

How hard are the tubes being run? I've seen EL34 being run hard last someone only a few years.

I know someone that leaves there tube amps on 24/7. This massively degrades lifespan.

 

 

Link to comment
Share on other sites

8 hours ago, seti said:

I know someone that leaves there tube amps on 24/7. This massively degrades lifespan.

excellent way to cook eggs

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...